Regeneration of platinum catalysts



Patented June 25, 19 35 I UNITED STATES PATENT OFFlC E f REGENERATION OF PLATINUM CATALYSTS Earl S. Ridlcr, Shaker Heights, Ohio, assignor to The Grasselli Chemical Company, Cleveland, Ohio, a corporation of Delaware NoD'rawing, ApplicationJune 22, 1933,

Serial No. 677,173

15 Claims. (01. 23-238) 'The'present invention relates to the regeneraacid, are considered to be volatile for the present tion of platinum catalysts in which the active purposes. Acids of this type which were found. platinum is deposited on 'an inert carrier and useful in my invention are, for instance, acetic consists in treating the spent catalyst with a acid, acrylic acid, butyric acid, benzoic acid,

' a liquid preparation of a volatile, organic carlactic acid, phthalic acid, propionic acid, oxalic boxylic acid. acid, succinic acid. These acids are-all commer- Platinum catalysts in which platinum is decially available and are soluble in various vola posited on an inert carrier are used mainly in tile solvents. j 7 gas phase reactions of which the oxidation of In the performance ofmy invention'I impreg- 10 S02 to S03 for the manufacture of sulfuric acid hate the spent catalyst Wi h a l q id p pfla- .10 is of the greatest importance. Supported platition of the desired carboxylic acid, if necessary num catalysts are used to some extent in other I separate the mass from the excess; liquidrand gas phase-reactions such as the oxidation of heat the impregnated masse u l h treating methanol to formaldehyde, the oxidation of agent is removed either byvolatilization, by restacetaldehyde to acetic acid, the reduction of pyrless decomp y other COIlVenieIlt m ans. idine to piperidine, the reduction of acid chlo- Two important points are to be observed in rides, reduction of acetylene homologues, etc. carrying o y regenerati n process: no residue My present invention is primarily intended for is to remainon the mass after treatment and the regeneration of platinum contact masses as the carboxyl fi ac d mu t fi s e applied at ordiused in the manufacture of sulfuric acid but it' nary temperature in liquid form, as a treatm n 20 can also be used for treating spent masses used of the pen a ys W Vapors of the CarbOX- in th r gas phase rea tion ylic acid does nothave the same regenerative Platinized, supported catalysts used in gas effect a a treatment with a liquid pr p ration. phase reactions consist commonly of finely di- C bQ ylic acids Which are liquid atordinars vided platinum deposited on a more or less inert t mpe atures, such as acetic a d, can be ap- 25 carrier such'as asbestos, magnesium sulfate, dip d directly th pent mass d but ingenelal atomaceous earth, silicic acid gel, etc.- These p 1301158 CODCeIltTated 50111310115 f h 3 5, rnasses do not have an indefinite life, or ecowat r being n all a s the p rred solvent, nomical activity, and must from time to time t oug I ca use Solutions n 311001101, acetone,

;- be regenerated or re-activated. benzol, etc. which can easily bejeliminated by so The regeneration process heretofore excluevaporation. sively used, as far as I know, consists in remov- When the catalyst carrier is insoluble in the ing the spent mass from the reaction converter, solvent used for the carboxylic acid, Ican simply screening out dust and scale, treating the mass Wash the catalyst directly in the converter with with a solution of aqua regia and then replacing thesolution takingcare that the mass iswell im- 35 the mass in the converter. The active period of p gnated with the'carboXylic acid, I then app y such a regenerated mass becomes shorter and heat to volatilize the acid and the solvent. shorter between successive regenerations and it In many instances, such a treatment would inmust finally be reworked to recover the platinum volve mechanical difiiculties in which cases I .40 and a new mass installed in the converters. prefer to remove the spent catalyst from the ap- 40 I have found that by treatment of spent platiparatus and treat it separately. This is particunum catalysts with liquid preparations of volalarly indicated when the catalyst carrier is solutile, organic carboxylic acids the activity of the ble in the treating agent. This case presentsitmasses is substantially restored and that the so self in the regeneration of platinized magnesium .45 regenerated masses can be successfully re-used sulfate catalysts as used in the oxidation of S02 to convert S02 to S03 or for catalyzing other to $03.. I remove this spent catalyst and spread gas phase reactions. it out on wooden trays where I spray it, for in- The organic carboxylic acids which I found stance, with an aqueous solution of acetic acid useful in my process are those acids which are untilthe mass is physically saturated with the substantially soluble in water, alcohol or other acid. The mass is then returned to the coneasily volatile solvent and which are completely verter, slowly heated up to the: reaction temvolatile at elevated temperatures, such as for inperature possibly while passing a stream of air stance below 400 0.; acids which are decomthrough the apparatus, whereby the acetic acid posed at such temperatures and leave no suband the Water are distilled. When the conver- .-'5-5 stantial residues on the masses, such as oxalic sion temperature is reached I introduce the sulfur dioxide and-air and the catalyst will be found to have recovered its activity.

The present application contains subject matter in common with my application Ser. No. 656,-

045, filed 'Feb. 9, 1933.

I claim:

The r e tin p l a num catalyst deposited on a carrier which comprises impregnating said catalyst with a liquid preparation of a volatile organic carboxylic acid and substantially completely removing said treating agent from said catalyst.

.2. The process'of regenerating aspentplatinum catalyst deposited on a carrier which comprises impregnating said catalyst witha solution of a volatile organicvcarboxylic acid in avolatilesolw I ent, and heating said catalyst to? completely eva- 'porate said carboxylic acid and saidsolv'ent;

3. The process of regenerating a spent platinum catalyst deposited on a carrier which comprises impregnating said catalyst with an aqueous solution'of an organic carboxylic acid and "heating -'s'aid-lcata'lyst tocom'pletely evaporate said 'carboxylic' acid and the water.

a 'Thelprocess of regenerating a; spent platinum catalyst depositedon a carrier which comprises impregnating said catalyst with acetic acid in liquid form and heating said catalystt'o completely evaporate' said acetic acid. g

T55 The process of regenerating a spentplatinum "catalyst {deposited one carrier which comprises ir'npreg'nating'said' catalyst with 'a solution of "srben'zo'ic acid in avolatile' solvent'and'heating said' catalyst to completel remove said acid and solv-.

, 533d p ed catalyst to temperatures of about'400-' C.

f8. The process of regenerating a'spent,"peileted, platinized magnesium sulfate catalystwhichfcjomprises-spraying a liquidpreparation of an organic, volatile carboxylic acid uponsaid mass and heat- *ing'the sprayed mass'until said liquid preparation :issubstantially completely removed "from" said mass.

' 9. e process of regenerating a spentplatinum catalyst deposited'on a carrier, said catalyst having been used in the oxidation of sulfur di- '7 oxide to sulfur trioxide, which comprises impregnating said catalyst with a liquid preparation of a volatile organic carboxylic acid and substantially completely removing said treating agent from said catalyst.

10. The process of regenerating a spent platinum catalyst-deposited on acarriensaidcatalyst having been used in the oxidation of sulfur dioxide tovsulfur trioxide, which comprises impregnating said catalyst with a solution of avolatile '11. The process'of regenerating a spent platicatalystdeposited on a carrier, said catalyst having been used in the oxidation of sulfur dioxide to sulfur trioxide', which comprises impregnatingsaid' catalyst with an aqueous solution of an organic carboxylic acid-and heating said cata-.

lyst to completely evaporate said carboxylic acid and said-waten l2.-The process 'ofregenerating ;a spent platinum catalyst deposited ona carrier, said catalyst I having been used in the oxidationof sulfur dioxide to sulfur trioxide, which comprises impregnating said catalyst with, acetic acid in'liquid form and heat-ingsaidcatalyst to completely. i

evaporate said acetic acid. 7 I

13 The process of regenerating asspent plati num catalyst deposited on-a carrier; said catalyst having been used in the oxidation of sulfur dioxide tosulfur trioxide, which comprises impregnating said catalyst with a'solution of 'benzoic acid in a volatile solvent, and heating said catalyst to completely removesaid acid-and solvent.

14. The processof regeneratingaspent platinum catalyst deposited on a carrier, said catalyst nating said catalyst with an aqueoussolution-of ration of an organic, volatile carboxylic acid upon said mass and heating the sprayed mass until said liquidpreparation is substantially completely removed from said mass.

EARL s. IRIDLER.

organic carboxylic acid in a volatile solvent, and heating saidcat a lystto completely evaporate said carboxylic aci'd an {said solvent.

having been used in the oxidation of sulfur 'div j oxide to sulfur trioxide, which comprisesimpregoxalic acid and cheating said impregnated catae V lyst until complete removal of saidacid and water. V 15. The process of regenerating a spent, pelleted, platinized magnesium sulfate catalyst, said catalyst having become inactive during its i .use in the oxidation of sulfur dioxide to sulfur trioxide which comprises spraying a liquid prepa- V 

